A read channel integrated circuit (IC) is one of the core electronic components in a modem magnetic recording system such as a hard disk drive. A read channel converts and encodes data to enable the heads to write data to the disk drive and then read back the data accurately. The disks in a drive typically have many tracks on them. Each track typically consists of mostly user or “read” data sectors, as well as control or “servo” data sectors embedded between the read sectors. The servo sectors help to position the magnetic recording head on a track so that the information stored in the read sectors is retrieved properly.
A typical magnetic recording system includes some mechanism for detecting servo data. However, a problem that inhibits the ability of such a detecting mechanism to reliably detect servo data during a disk seek is a condition referred to as “radial incoherence.” Radial incoherence (RI) refers to the offset in timing between radially adjacent servo tracks. From a signal processing point of view, quick phase changes and some signal loss are characteristics of RI.
Thus, in magnetic recording systems, there is a need for techniques which improve servo data detection performance in the presence of radial incoherence.